We found it difficult to get an early ADR for the Tusker House Breakfast. The earlier the better, so you can be done near the time of rope drop to walk a few feet and get onto the safari ride. This was our favorite character breakfast. (FYI - we ate lunch here also and the buffet was awesome for it as well.)
We did 6 character breakfasts that week - Crystal Palace - which is in refurb so you would have to try Liberty Tree Tavern for MK. It's great being in the park before it opens. Chef Mickey's was also good. We really liked Ohana's for breakfast. With two girls, the princess breakfast at Epcot is a must for us. And although it doesn't get many good reviews (mainly lunch and dinner) we enjoyed Hollywood and Vine at Hollywood studios.
The Tusker House breakfast is a must do for our family now. We tried it a few weeks ago for the first time and loved it. The buffet is large and has a lot of variety. Donald (outside for pics), Daisy, Goofy and Mickey were the characters. (I've heard Minnie shows from time to time.)
We also ate at Sci-fi and 50's. Sci-fi was OK, but nothing really special. 50's Prime Time Cafe was great. We had a great server (the kind who gets on you for elbows on the table, ordering too many refills for drinks, etc) who was very funny. She only gets onto the adults, so the kids loved it! The fried chicken was the best I ever had (4 pieces - a ton of food). My husband had the pot roast (and my chicken breast) and thought it was rather good as well.
We were not able to get Le Cellier ADR's until about a week out from our trip. It was well worth the wait. The NY strip was one of the best steaks we have ever had (and we love steak), and the bread was awesome as well. This too will be a must do for us in the future. My husband wants to eat here atleast once a day on our next trip.
I don't know how hard it is to get reservations for January, but we only had a 90 day window and lots of people trying to get reservations for their
free dining offer that was going on at the same time we were there.
Good luck on getting the ADR's you are looking for.